Aqueous polymer latexes have been employed in the formulation of paper coatings. Even with conventional pigments, such coatings have frequently had more gloss than was desired. It is commonplace to incorporate flattening or dulling agents into the composition to reduce that gloss. Typical of such agents are calcined clays or large particle size calcium carbonate.
Macrospherical particles of vinyl ester resins are disclosed in U.S. Pat. No. 3,799,903. A method for preparing such particles is also taught. That process involves the preparation of a three-phase mixture, one of the phases being an inorganic material. The resulting particles were said to be useful for incorporating biologically active materials for controlled release of that active agent.
The need for improved dulling agents in paper coating led to a consideration of vinyl ester resin macrospheres for that purpose. However, it would be desirable to have such spheres capable of existing both with and without inorganic materials. Also, it would be desirable to have a less complicated process for preparing such macrospheres.